Specifications

16
SERVICE AND MAINTENANCE
64
Rebuilding the Operational Valves
The valves that are used on the Dura-Cyl/Cryo-Cyl
models have a spring loaded rotary stem. This auto-
matically compensates for thermal shrinkage and wear.
When a defective valve is suspected, follow this pro-
cedure to repair it.
Disassembly and Repair Procedure
Caution: To avoid binding due to freezing at cryogenic
temperatures, entry of moisture into the upper valve
stem area must be prevented. Seals, gaskets and
washers must be in good condition and installed
carefully and properly. Torque recommendations
must be strictly followed.
Disassembly
1. Open valve by turning handwheel counter-
clockwise as far as it will go to release any
trapped gas in the system.
CAUTION: Do not apply force after valve is
fully open.
2. Using a screwdriver, remove handwheel screw
and washer (Items 3 & 14) by turning counter-
clockwise to allow removal of spring retainer,
washer, spring, seal washer, seal, handwheel,
and bonnet washers (Items 2, 8,4, 13, 10, 1 and 7).
Discard these parts.
3. Using a large adjustable wrench to hold valve
body, remove and discard bonnet (Item 5) by
turning counterclockwise with a 15/16" socket
wrench that is capable of developing at least
1000 in/lbs. torque.
4.
Remove these parts from the valve body and
discard: stem, stem gasket, seat disc and nipple
assembly, and bushing.
5. Inspect body and clean if necessary, be sure
interior and seal areas are free of dirt, residue,
and foreign particles.
CAUTION: Do not scratch or mar internal sur-
faces of valve.
Reassembly
1. Partially thread seat disc and nipple assembly
(Item 12) (seat disc first), into large end of
bushing (Item 9), leaving tang of nipple as-
sembly exposed about 1/3" beyond top of
bushing (nipple must rotate freely in bushing).
2. Insert seat disc and nipple assembly (Item 12)
(seat disc first), with attached bushing, into
valve body until properly seated.
3. Place stem gasket (Item 15) carefully over
stem (Item 6) convex side facing downward.
4. Insert slotted end of stem into valve body,
making sure that slot fully engages tang of seat
disc and nipple assembly.
5. Place bonnet (Item 5) over stem and, while
holding square end of stem to keep it from
turning, thread bonnet into valve body. Hold
body with one wrench and, using another
wrench (15/16 socket), tighten bonnet to 1000
in/lbs. torque.
CAUTION: Hex section of bonnet (Item 5) must
be free of burrs or raised edges and top of bon-
net must be absolutely flat to provide an effective
seal with bonnet gasket washer (Item 7).
6. Install bonnet washer (Item 7) over stem (Item
6) on bonnet.
11
9
12
6
15
5
7
10
1
13
4
2
14
3
8
Item Description Qty Part Number
1 Handwheel 1
2
Spring Retainer
1
3 Screw 1
4
Spring
1
5
Bonnet
1
6 Stem 1
7 Bonnet Washer 2
8 Washer 1
9 Bushing 1
10 Seal 1
11
Body and Tube 1
12 Seat Disc & Nipple Assembly 1
13
Seal Washer
1
14
Washer
1
15 Gasket 1
Figure FF
Included in
Valve Repair Kit
P/N 9715759
(Except Item 11
which is not
available as a
repair part).